/*
    This file is part of Konsole, an X terminal.

    Copyright 2007-2008 by Robert Knight <robertknight@gmail.com>
    Copyright 1997,1998 by Lars Doelle <lars.doelle@on-line.de>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301  USA.
*/

#ifndef EMULATION_H
#define EMULATION_H

// System
#include <stdio.h>

// Qt
#include <QKeyEvent>
//#include <QPointer>
#include <QTextCodec>
#include <QTextStream>
#include <QTimer>

// Konsole
//#include "konsole_export.h"
#define KONSOLEPRIVATE_EXPORT

namespace Konsole
{

  class KeyboardTranslator;
  class HistoryType;
  class Screen;
  class ScreenWindow;
  class TerminalCharacterDecoder;

  /**
   * This enum describes the available states which
   * the terminal emulation may be set to.
   *
   * These are the values used by Emulation::stateChanged()
   */
  enum
  {
    /** The emulation is currently receiving user input. */
    NOTIFYNORMAL = 0,
    /**
     * The terminal program has triggered a bell event
     * to get the user's attention.
     */
    NOTIFYBELL = 1,
    /**
     * The emulation is currently receiving data from its
     * terminal input.
     */
    NOTIFYACTIVITY = 2,

    // unused here?
    NOTIFYSILENCE = 3
  };

  /**
   * Base class for terminal emulation back-ends.
   *
   * The back-end is responsible for decoding an incoming character stream and
   * producing an output image of characters.
   *
   * When input from the terminal is received, the receiveData() slot should be called with
   * the data which has arrived.  The emulation will process the data and update the
   * screen image accordingly.  The codec used to decode the incoming character stream
   * into the unicode characters used internally can be specified using setCodec()
   *
   * The size of the screen image can be specified by calling setImageSize() with the
   * desired number of lines and columns.  When new lines are added, old content
   * is moved into a history store, which can be set by calling setHistory().
   *
   * The screen image can be accessed by creating a ScreenWindow onto this emulation
   * by calling createWindow().  Screen windows provide access to a section of the
   * output.  Each screen window covers the same number of lines and columns as the
   * image size returned by imageSize().  The screen window can be moved up and down
   * and provides transparent access to both the current on-screen image and the
   * previous output.  The screen windows emit an outputChanged signal
   * when the section of the image they are looking at changes.
   * Graphical views can then render the contents of a screen window, listening for notifications
   * of output changes from the screen window which they are associated with and updating
   * accordingly.
   *
   * The emulation also is also responsible for converting input from the connected views such
   * as keypresses and mouse activity into a character string which can be sent
   * to the terminal program.  Key presses can be processed by calling the sendKeyEvent() slot,
   * while mouse events can be processed using the sendMouseEvent() slot.  When the character
   * stream has been produced, the emulation will emit a sendData() signal with a pointer
   * to the character buffer.  This data should be fed to the standard input of the terminal
   * process.  The translation of key presses into an output character stream is performed
   * using a lookup in a set of key bindings which map key sequences to output
   * character sequences.  The name of the key bindings set used can be specified using
   * setKeyBindings()
   *
   * The emulation maintains certain state information which changes depending on the
   * input received.  The emulation can be reset back to its starting state by calling
   * reset().
   *
   * The emulation also maintains an activity state, which specifies whether
   * terminal is currently active ( when data is received ), normal
   * ( when the terminal is idle or receiving user input ) or trying
   * to alert the user ( also known as a "Bell" event ).  The stateSet() signal
   * is emitted whenever the activity state is set.  This can be used to determine
   * how long the emulation has been active/idle for and also respond to
   * a 'bell' event in different ways.
   */
  class KONSOLEPRIVATE_EXPORT Emulation : public QObject
  {
      Q_OBJECT

    public:

      /** Constructs a new terminal emulation */
      Emulation();
      ~Emulation() override;

      /**
       * Creates a new window onto the output from this emulation.  The contents
       * of the window are then rendered by views which are set to use this window using the
       * TerminalDisplay::setScreenWindow() method.
       */
      ScreenWindow *createWindow();

      /** Returns the size of the screen image which the emulation produces */
      QSize imageSize() const;

      /**
       * Returns the total number of lines, including those stored in the history.
       */
      int lineCount() const;

      /**
       * Sets the history store used by this emulation.  When new lines
       * are added to the output, older lines at the top of the screen are transferred to a history
       * store.
       *
       * The number of lines which are kept and the storage location depend on the
       * type of store.
       */
      void setHistory( const HistoryType & );
      /** Returns the history store used by this emulation.  See setHistory() */
      const HistoryType &history() const;
      /** Clears the history scroll. */
      void clearHistory();

      /**
       * Copies the output history from @p startLine to @p endLine
       * into @p stream, using @p decoder to convert the terminal
       * characters into text.
       *
       * \param decoder A decoder which converts lines of terminal characters with
       * appearance attributes into output text.  PlainTextDecoder is the most commonly
       * used decoder.
       * \param startLine Index of first line to copy
       * \param endLine Index of last line to copy
       */
      virtual void writeToStream( TerminalCharacterDecoder *decoder, int startLine, int endLine );

      /** Returns the codec used to decode incoming characters.  See setCodec() */
      const QTextCodec *codec() const { return _codec; }
      /** Sets the codec used to decode incoming characters.  */
      void setCodec( const QTextCodec * );

      /**
       * Convenience method.
       * Returns true if the current codec used to decode incoming
       * characters is UTF-8
       */
      bool utf8() const
      { Q_ASSERT( _codec ); return _codec->mibEnum() == 106; }


      /** TODO Document me */
      virtual char eraseChar() const;

      /**
       * Sets the key bindings used to key events
       * ( received through sendKeyEvent() ) into character
       * streams to send to the terminal.
       */
      void setKeyBindings( const QString &name );
      /**
       * Returns the name of the emulation's current key bindings.
       * See setKeyBindings()
       */
      QString keyBindings() const;

      /**
       * Copies the current image into the history and clears the screen.
       */
      virtual void clearEntireScreen() = 0;

      /** Resets the state of the terminal. */
      virtual void reset() = 0;

      /**
       * Returns true if the active terminal program wants
       * mouse input events.
       *
       * The programUsesMouseChanged() signal is emitted when this
       * changes.
       */
      bool programUsesMouse() const;

    public slots:

      /** Change the size of the emulation's image */
      virtual void setImageSize( int lines, int columns );

      /**
       * Interprets a sequence of characters and sends the result to the terminal.
       * This is equivalent to calling sendKeyEvent() for each character in @p text in succession.
       */
      virtual void sendText( const QString &text ) = 0;

      /**
       * Interprets a key press event and emits the sendData() signal with
       * the resulting character stream.
       */
      virtual void sendKeyEvent( QKeyEvent * );

      /**
       * Converts information about a mouse event into an xterm-compatible escape
       * sequence and emits the character sequence via sendData()
       */
      virtual void sendMouseEvent( int buttons, int column, int line, int eventType );

      /**
       * Sends a string of characters to the foreground terminal process.
       *
       * \param string The characters to send.
       * \param length Length of @p string or if set to a negative value, @p string will
       * be treated as a null-terminated string and its length will be determined automatically.
       */
      virtual void sendString( const char *string, int length = -1 ) = 0;

      /**
       * Processes an incoming stream of characters.  receiveData() decodes the incoming
       * character buffer using the current codec(), and then calls receiveChar() for
       * each unicode character in the resulting buffer.
       *
       * receiveData() also starts a timer which causes the outputChanged() signal
       * to be emitted when it expires.  The timer allows multiple updates in quick
       * succession to be buffered into a single outputChanged() signal emission.
       *
       * \param buffer A string of characters received from the terminal program.
       * \param len The length of @p buffer
       */
      void receiveData( const char *buffer, int len );

    signals:

      /**
       * Emitted when a buffer of data is ready to send to the
       * standard input of the terminal.
       *
       * \param data The buffer of data ready to be sent
       * \param len The length of @p data in bytes
       */
      void sendData( const char *data, int len );

      /**
       * Requests that sending of input to the emulation
       * from the terminal process be suspended or resumed.
       *
       * \param suspend If true, requests that sending of
       * input from the terminal process' stdout be
       * suspended.  Otherwise requests that sending of
       * input be resumed.
       */
      void lockPtyRequest( bool suspend );

      /**
       * Requests that the pty used by the terminal process
       * be set to UTF 8 mode.
       *
       * TODO: More documentation
       */
      void useUtf8Request( bool );

      /**
       * Emitted when the activity state of the emulation is set.
       *
       * \param state The new activity state, one of NOTIFYNORMAL, NOTIFYACTIVITY
       * or NOTIFYBELL
       */
      void stateSet( int state );

      /** TODO Document me */
      void zmodemDetected();


      /**
       * Requests that the color of the text used
       * to represent the tabs associated with this
       * emulation be changed.  This is a Konsole-specific
       * extension from pre-KDE 4 times.
       *
       * TODO: Document how the parameter works.
       */
      void changeTabTextColorRequest( int color );

      /**
       * This is emitted when the program running in the shell indicates whether or
       * not it is interested in mouse events.
       *
       * \param usesMouse This will be true if the program wants to be informed about
       * mouse events or false otherwise.
       */
      void programUsesMouseChanged( bool usesMouse );

      /**
       * Emitted when the contents of the screen image change.
       * The emulation buffers the updates from successive image changes,
       * and only emits outputChanged() at sensible intervals when
       * there is a lot of terminal activity.
       *
       * Normally there is no need for objects other than the screen windows
       * created with createWindow() to listen for this signal.
       *
       * ScreenWindow objects created using createWindow() will emit their
       * own outputChanged() signal in response to this signal.
       */
      void outputChanged();

      /**
       * Emitted when the program running in the terminal wishes to update the
       * session's title.  This also allows terminal programs to customize other
       * aspects of the terminal emulation display.
       *
       * This signal is emitted when the escape sequence "\033]ARG;VALUE\007"
       * is received in the input string, where ARG is a number specifying what
       * should change and VALUE is a string specifying the new value.
       *
       * TODO:  The name of this method is not very accurate since this method
       * is used to perform a whole range of tasks besides just setting
       * the user-title of the session.
       *
       * \param title Specifies what to change.
       * <ul>
       * <li>0 - Set window icon text and session title to @p newTitle</li>
       * <li>1 - Set window icon text to @p newTitle</li>
       * <li>2 - Set session title to @p newTitle</li>
       * <li>11 - Set the session's default background color to @p newTitle,
       *         where @p newTitle can be an HTML-style string ("#RRGGBB") or a named
       *         color (e.g., 'red', 'blue').
       *         See http://doc.trolltech.com/4.2/qcolor.html#setNamedColor for more
       *         details.
       * </li>
       * <li>31 - Supposedly treats @p newTitle as a URL and opens it (NOT IMPLEMENTED)</li>
       * <li>32 - Sets the icon associated with the session.  @p newTitle is the name
       *    of the icon to use, which can be the name of any icon in the current KDE icon
       *    theme (e.g., 'konsole', 'kate', 'folder_home')</li>
       * </ul>
       * \param newTitle Specifies the new title
       */

      void titleChanged( int title, const QString &newTitle );

      /**
       * Emitted when the program running in the terminal changes the
       * screen size.
       */
      void imageSizeChanged( int lineCount, int columnCount );

      /**
       * Emitted when the terminal program requests to change various properties
       * of the terminal display.
       *
       * A profile change command occurs when a special escape sequence, followed
       * by a string containing a series of name and value pairs is received.
       * This string can be parsed using a ProfileCommandParser instance.
       *
       * \param text A string expected to contain a series of key and value pairs in
       * the form:  name=value;name2=value2 ...
       */
      void profileChangeCommandReceived( const QString &text );

      /**
       * Emitted when a flow control key combination ( Ctrl+S or Ctrl+Q ) is pressed.
       * \param suspendKeyPressed TRUE if Ctrl+S was pressed to suspend output or Ctrl+Q to
       * resume output.
       */
      void flowControlKeyPressed( bool suspendKeyPressed );

    protected:
      virtual void setMode( int mode ) = 0;
      virtual void resetMode( int mode ) = 0;

      /**
       * Processes an incoming character.  See receiveData()
       * @p ch A unicode character code.
       */
      virtual void receiveChar( int ch );

      /**
       * Sets the active screen.  The terminal has two screens, primary and alternate.
       * The primary screen is used by default.  When certain interactive programs such
       * as Vim are run, they trigger a switch to the alternate screen.
       *
       * \param index 0 to switch to the primary screen, or 1 to switch to the alternate screen
       */
      void setScreen( int index );

      enum EmulationCodec
      {
        LocaleCodec = 0,
        Utf8Codec   = 1
      };
      void setCodec( EmulationCodec codec ); // codec number, 0 = locale, 1=utf8


      QList<ScreenWindow *> _windows;

      Screen *_currentScreen;  // pointer to the screen which is currently active,
      // this is one of the elements in the screen[] array

      Screen *_screen[2];      // 0 = primary screen ( used by most programs, including the shell
      //                      scrollbars are enabled in this mode )
      // 1 = alternate      ( used by vi , emacs etc.
      //                      scrollbars are not enabled in this mode )


      //decodes an incoming C-style character stream into a unicode QString using
      //the current text codec.  (this allows for rendering of non-ASCII characters in text files etc.)
      const QTextCodec *_codec;
      QTextDecoder *_decoder;
      const KeyboardTranslator *_keyTranslator; // the keyboard layout

    protected slots:
      /**
       * Schedules an update of attached views.
       * Repeated calls to bufferedUpdate() in close succession will result in only a single update,
       * much like the Qt buffered update of widgets.
       */
      void bufferedUpdate();

    private slots:

      // triggered by timer, causes the emulation to send an updated screen image to each
      // view
      void showBulk();

      void usesMouseChanged( bool usesMouse );

    private:
      bool _usesMouse;
      QTimer _bulkTimer1;
      QTimer _bulkTimer2;

  };

}

#endif // ifndef EMULATION_H
